A comprehensive overview of grain development in Brachypodium distachyon variety Bd21

A detailed and comprehensive understanding of seed reserve accumulation is of great importance for agriculture and crop improvement strategies. This work is part of a research programme aimed at using Brachypodium distachyon as a model plant for cereal grain development and filling. The focus was on the Bd21-3 accession, gathering morphological, cytological, and biochemical data, including protein, lipid, sugars, starch, and cell-wall analyses during grain development. This study highlighted the existence of three main developmental phases in Brachypodium caryopsis and provided an extensive description of Brachypodium grain development. In the first phase, namely morphogenesis, the embryo developed rapidly reaching its final morphology about 18 d after fertilization (DAF). Over the same period the endosperm enlarged, finally to occupy 80% of the grain volume. During the maturation phase, carbohydrates were continuously stored, mainly in the endosperm, switching from sucrose to starch accumulation. Large quantities of β-glucans accumulated in the endosperm with local variations in the deposition pattern. Interestingly, new β-glucans were found in Brachypodium compared with other cereals. Proteins (i.e. globulins and prolamins) were found in large quantities from 15 DAF onwards. These proteins were stored in two different sub-cellular structures which are also found in rice, but are unusual for the Pooideae. During the late stage of development, the grain desiccated while the dry matter remained fairly constant. Brachypodium exhibits some significant differences with domesticated cereals. Beta-glucan accumulates during grain development and this cell wall polysaccharide is the main storage carbohydrate at the expense of starch

An exploration of how plant and soil characteristics shape the Hypericum perforatum microbiome in three habitats

Saint John’s wort, Hypericum perforatum, is a medicinally and ecologically important perennial plant species that has a broad global distribution. Despite the species’ importance, little is known about the factors that structure its microbial communities and the identity of microbes that enhance plant growth and fitness. Here we aim to describe the microbial communities associated with Hypericum perforatum and elucidate factors that structure these communities. We collected H. perforatum root samples in three adjacent habitat types: wet and dry alvars (two types of limestone barren) and fallow agricultural fields (i.e. old-fields), in Jefferson County, New York. We used high-throughput amplicon sequencing to characterize the bacterial and fungal root microbiome. We also quantified aspects of the plant phenotype and soil characteristics to evaluate habitat variables that correlate with the root microbiome. Habitat and plant height were correlated with shifts in microbial community composition. We identified two bacterial taxa positively associated with plant height, both belonging to the bacterial phylum Actinobacteria. This work contributes to our understanding of the environmental determinants of microbial community composition and identifies microbial taxa that may be important in promoting plant growth